More robust handling of URLerrors:
try to get the error code when it's available.
Eventually we'd like to be able to detect network-down conditions
and loop prompting the user to try to reset the network.
(If sl4a allows prompting ...)
Also, strip # named anchors from both fetched URL and saved filename.
Remove some of the verbose comments on URLError
and how to debug URLError conditions. I left the comments in
intentionally the first time, so those suggestions will be available
in the git history if anyone ever needs them. But they don't need
to clog the running code forever.